A plate heat exchanger is defined as a heat exchanger in which a heat transfer element is a plate. Compared with a conventional heat exchanger, the plate heat exchanger has a compact structure, and is made from an aluminum alloy material, which is very light. Also, since the high thermal conductivity of the plate, the plate heat exchanger has high efficiency. Therefore, the plate heat exchanger has a high adaptive ability, which may be used in heat exchange between various fluids and phase change heat exchange in which aggregate state change occurs, and may be adapted to different heat exchange conditions such as countercurrent flow, cross-flow, multi-stream flow and multi-pass flow by arrangement and combination of flow passages, and can meet heat exchange requirements of a large-scale equipment by series connection, parallel connection or combination of series connection and parallel connection between units.
Currently, the plate heat exchanger is widely used in vehicles. One of applications of the plate heat exchanger is used for heat exchanging between cooling oil of a gearbox and coolant of an engine, i.e., the plate heat exchanger is used as an oil cooler, and the cooling oil of the gearbox passes the oil cooler or not under control of a thermostatic valve, in this way, the cooling oil of the gearbox is cooled. The thermostatic valve is in communication with the gearbox and the oil cooler respectively via pipelines.
With increasingly high requirements imposed on the performance of the vehicle, the temperature control requirement to the cooling oil of the gearbox is also accordingly high. Not only the cooling oil of the gearbox needs to be cooled during traveling of an vehicle, but also the cooling oil of the gearbox needs to be heated when the vehicle is just started, and particularly when the vehicle is started in a low temperature environment, so as to maintain the cooling oil of the gearbox in at an appropriate working temperature. Furthermore, with an increasing travel of the vehicle, cooling water of an engine may fail to decrease the temperature of the cooling oil of the gearbox.
Further, a mounting space in the vehicle is limited, and an increasing of parts and components may increase the difficulty of mounting.
Therefore, a technical issue to be addressed presently is to provide a heat exchange device which needs a reduced mounting space, and facilitates the temperature regulation of cooling oil of the gearbox.